Field of the Invention
The present invention relates to a method for producing a semi-finished web product comprising a transversely extensible elastic laminar web material provided with connection formations.
The present description has been developed with particular reference to the possible application of the transversely extensible elastic laminar web material in the production of disposable absorbent sanitary products in the form of wearable pants, such as, for example, diapers for children and/or absorbent sanitary articles for incontinent adults.
Description of Prior Art
For some time, absorbent sanitary articles wearable as pants have a configuration that comprises a rectangular-shaped central body or chassis that is capable of having a basin arrangement around the crotch region of the user and at least one pair of side panels, which extend on opposite sides of at least one of the ends, front or rear, of the article provided with connection or closing formations capable of joining together the front and rear ends of the chassis of the absorbent article around the user's waistline.
There are many patent documents that address the problem of producing suitable materials for the production of side panels capable of combining characteristics of elastic extensibility as well as breathability.
An important development in the production of these materials is outlined in the document TO2008A000325, owned by the applicant, in which the disclosures are provided to produce an extensible laminar material obtained by coupling together two sheets of non-woven fabric with an interposed layer of elastic material, using a combination of adhesive lines and welds.
In any case, any connection formations necessary for joining together the front and rear ends of the sanitary article must be applied on the material intended to be used to produce the side panels, thus giving it the characteristic underpants conformation.
As is known, the connection formations attached to the ends of the side panels, precisely due to the function that they perform—namely to maintain the absorbent article closed in its underpants conformation—are subject to very high stresses, which can easily lead to breakage of the joint between the material of the side panels and the connection formation itself.
To resolve this problem, the specialized manufacturers—many years ago—developed said connection formations with a Y-shape. These connection formations have a multilayer structure, which allows them to trap the side panel material between two laminar elements provided with a generous layer of adhesive. An example of a Y-shaped connection formation advantageously used for producing disposable sanitary articles is described in U.S. Pat. No. 4,369,786 entitled “Refastenable adhesive closure for disposable diapers or briefs” owned by the Avery International Corporation, Pasadena, Calif.
These solutions, while having led to satisfactory results, present problems related precisely to the complexity of their structure and to the need to use large quantities of adhesive which, as is known, belongs to a category of very polluting materials that have a high environmental footprint (carbon footprint). In addition to the above, the complex structure of the Y-shaped connection formations is reflected in a high cost, which is transferred to the selling price of the sanitary article.
To the above, it should be added that to produce the elasticized side panels, the use of significant quantities of adhesive may also be necessary.
Accordingly, the current state-of-the-art in the production of sanitary articles with elasticized side panels provided with connection formations presents problems related to the complexity and to the massive use of adhesives that it entails.